#include<iostream>
#include<iostream>
#include<vector>
#include<semaphore.h>
#include<pthread.h>
using namespace std;

const static int defaultcap=5;

template<class T>
class RingQueue
{
private:
    void P(sem_t &sem)
    {
        sem_wait(&sem);
    }
    void V(sem_t &sem)
    {
        sem_post(&sem);
    }
    void Lock(pthread_mutex_t &mutex)
    {
        pthread_mutex_lock(&mutex);
    }
    void Unlock(pthread_mutex_t &mutex)
    {
        pthread_mutex_unlock(&mutex);
    }
public:
    RingQueue(int cap=defaultcap)
    :ringqueue_(cap),cap_(cap),c_step_(0),p_step_(0)
    {
        sem_init(&cdata_sem_,0,0);
        sem_init(&pspace_sem_,0,cap);
        pthread_mutex_init(&c_mutex_,nullptr);
        pthread_mutex_init(&p_mutex_,nullptr);
    }
    ~RingQueue()
    {
        sem_destroy(&cdata_sem_);
        sem_destroy(&pspace_sem_);
        pthread_mutex_destroy(&c_mutex_);
        pthread_mutex_destroy(&p_mutex_);
    }
    void Push(const T&in)    //生产
    {

        P(pspace_sem_);       //信号量的申请是原子的
        Lock(p_mutex_);
        ringqueue_[p_step_]=in;
        //位置后移，维持环形特征
        p_step_++;
        p_step_%=cap_;
        Unlock(p_mutex_);
        V(cdata_sem_);      
    }
    void Pop(T *out)     //消费
    {
        P(cdata_sem_);
        Lock(c_mutex_);
        *out=ringqueue_[c_step_];
        //位置后移，维持环形特性
        c_step_++;
        c_step_%=cap_;
        Unlock(c_mutex_);
        V(pspace_sem_);      
    }
private:
    vector<T> ringqueue_;
    int cap_;

    int c_step_;   //消费者下标
    int p_step_;   //生产者下标

    sem_t cdata_sem_;   //消费者关注的数据资源
    sem_t pspace_sem_;  //生产者关注的空间资源

    pthread_mutex_t c_mutex_;
    pthread_mutex_t p_mutex_;
};